Question

Answer 1

Bài 31:

a: \(\dfrac{2}{5}\cdot\dfrac{3}{7}=\dfrac{6}{35}\)

\(\dfrac{4}{7}\cdot\dfrac{3}{4}=\dfrac{3}{7}\)

\(\dfrac{4}{9}\cdot\dfrac{3}{10}=\dfrac{12}{90}=\dfrac{2}{15}\)

\(2\cdot\dfrac{5}{18}=\dfrac{5}{9}\)

b: \(\dfrac{3}{8}:\dfrac{7}{5}=\dfrac{3}{8}\cdot\dfrac{5}{7}=\dfrac{15}{56}\)

\(\dfrac{3}{4}:\dfrac{9}{10}=\dfrac{3}{4}\cdot\dfrac{10}{9}=\dfrac{30}{36}=\dfrac{5}{6}\)

\(\dfrac{7}{8}:2=\dfrac{7}{32}\)

\(6:\dfrac{2}{3}=6\cdot\dfrac{3}{2}=9\)

c: \(=\dfrac{15}{15\cdot9}=\dfrac{1}{9}\)

\(=\dfrac{15}{16}\cdot\dfrac{8}{3}\cdot\dfrac{3}{4}=\dfrac{15}{16}\cdot2=\dfrac{15}{8}\)